How would a manual DCA work better in a ETF like ARKK, ARKG, CQQ if the prices keep going up?

For such etfs, especially growth ones like ARK Invest, it would be better to just set a date and buy in on that date every month, regardless of the price. Instead of trying to time the market by waiting for a correction, just buy every month regardless of the price. High can go higher.

This is the reason why lump sum investments actually beat DCA investing about 2/3 of the time when looking over a 12 month period. Over longer periods, this win rate increases further. The only time DCA beats lump sum (usually), is in declining markets, in bull markets, lump sum will often turn out better.

As such, if you do have the funds on hand and your heart can handle it, I would generally advise lump sum investing over DCA.